1. Field of the Invention
The present invention relates to a speaker cabinet and a speaker using the same. To be more specific, the present invention relates to a speaker cabinet and a speaker using the same capable of producing a sound image space more natural and full of reality.
2. Description of the Related Art
The design principles for speaker cabinets have been polarized into two ways of thinking: the concept that the radiation sound from the cabinet is unnecessary and should be suppressed so as to reverberate as little as possible; and the concept that the radiation sound from the cabinet should be positively allowed to reverberate to attain a rich, full-bodied sound. As means for realizing the latter concept, the thickness of the plate materials forming the cabinet is reduced, or well-reverberating plate materials are used. For example, there has been proposed a cabinet whose plate materials are composed of resonance materials for musical instruments (see Japanese Utility Model Application No. Hei 6-23394). According to Japanese Utility Model Application No. Hei 6-23394, a front plate and a back plate are attached to a body portion formed of a cylindrical member to form a hollow cylindrical cabinet, and a speaker unit is mounted to the central portion of the front plate of the cabinet, thereby realizing a speaker producing a natural sound.
However, the speaker cabinet as disclosed in Japanese Utility Model Application No. Hei 6-23394 has the following problems. That is, of the radiation sounds from the resonance portions of a musical instrument such as a guitar, the radiation sound from the front plate (and the back plate) is larger than the radiation sound from the body portion. This is due to the fact that the front plate (and the back plate) are formed of a relatively thin plate material (typically having a thickness of approximately 3 mm) and that the musical instrument has a so-called drum structure whose body portion constrains the peripheral portion and whose central portion is easily allowed to vibrate. As a result, the vibration of the strings is richly flavored, and a full-bodied timbre is obtained. In contrast, in the speaker cabinet as disclosed in Japanese Utility Model Application No. Hei 6-23394, it is necessary to impart an appropriate strength allowing supporting of the speaker unit to the portion where the speaker unit is mounted (that is, front plate of the cabinet, which corresponds to the front plate of the guitar), so the thickness of the plate material must be increased. As a result, the radiation sound from the front plate is reduced, and no full-bodied sound is reproduced. If the cabinet is prepared with the thickness of the front plate being almost as thin as that of a musical instrument, the requisite strength for supporting the speaker cannot be obtained, which means that there are cases where the cabinet cannot be put into practical use, and the weight of the speaker must be limited (that is, use of a high-power speaker is impossible). Further, if, in such a cabinet, the drive power for the speaker unit is increased, an abnormal vibration of the front plate will be caused in some cases, resulting in generation of noise. Even if the speaker unit is mounted in a satisfactory manner, the weight of the front plate as a whole increases due to the weight of the speaker unit itself, so the vibration of the front plate is rather limited, and no full-bodied sound can be reproduced.